Wire-dot impact type printer

Abstract

In a wire-dot impact type printer, a single electric motor is employed for rotating a platen provided at a periphery thereof with a plurality of ink saturated members to thereby change a color to be applied to a printing paper, as well as for rotating tractors cooperated with feed rollers to thereby transport the printing paper in a predetermined direction. A transmission mechanism for transmitting rotational movement of the motor to the tractors comprises a switch disc rotated together with the motor and having a circular periphery thereof which is half toothed and half untoothed, and a clutch composed of a first rotating disc rotated due to engagement with the toothed half portion of the switch disc and a second rotating disc capable of rotating together with the first rotating disc being rotated in one direction to thereby cause the tractors to rotate for the paper feeding operation, but prevented from rotation when the first rotating unit is rotated in the opposite direction. The platen is rotatable in both directions by the reversible motor while the switch disc is positioned such that the first rotating disc of the clutch confronts the untoothed half portion of the switch and is not in mesh with the toothed half portion, which makes the tractors inoperative so that the printing paper remains standstill.

What is claimed: 
     
       1. A printer comprising a rotary platen provided on a periphery thereof a plurality of members saturated with different color inks; a printing head arranged opposite to said platen so as to cooperate with said platen to apply an ink of a specific color to a printing paper adapted to pass therebetween; first means for rotating said platen; second means for transporting said printing paper relative to said platen and said printing head; and drive means driven under a predetermined control to operate said first and second means through first and second transmission means respectively; wherein said second transmission means comprises (a) switch means including a rotary member operatively connected to said drive means and rotated in one or the opposite direction in dependence upon the controlled drive movement of said drive means, said rotary member having gear teeth formed in a limited range on a periphery thereof, and   (b) clutch means provided between said switch means and said paper transporting means, said clutch means being operative to transmit the drive movement of said drive means to said paper transporting means when said gear teeth of said rotary member come to engage said clutch means while said rotary member is rotated in one direction, and being inoperative with respect to said paper transporting means when said rotary member is rotated in the opposite direction.   
     
     
       2. The printer according to claim 1 wherein said clutch means comprises a first rotating member which may be engaged with said gear teeth of said rotary member to be rotated thereby, a second rotating member operatively connected to said first rotating member to transport the rotating movement of said first rotating member to said paper transporting means only when said first rotating member is rotated in one direction, and means for disconnecting said second rotating member from said first rotating member when said first rotating member is rotated in the opposite direction. 
     
     
       3. The printer according to claim 2 wherein said gear teeth are continuously provided on a half range of a periphery of said rotary member. 
     
     
       4. The printer according to claim 1 wherein said drive means is a reversible motor, and said platen rotating means is directly connected to said reversible motor.